Have you gone "contactless" yet? During the last few months, millions of people have received new-style debit and credit cards which allow them to pay for low-value items such as their morning coffee or lunchtime sandwiches by simply waving their plastic over a reader at the till.

It's estimated there are now around 10m in the nation's wallets and purses – you'll know you've got one if it displays the "wave" symbol, shown above – with this number set to rise to 14m by the end of December, and 25m by the end of 2012.

Contactless cards have been hyped as the next big thing in banking and retail because they let people pay for less costly items (£15 or less) without having to key in a pin number or scrabble around for cash.

It's a payment revolution that's been brewing since 2007. Up until recently it has all been rather "London-centric", and largely confined to coffee shops and eateries.

Now the technology is starting to get a nationwide presence. A host of big-name retailers are either trialling it or rolling it out, including Tesco, the Co-op, Boots, Ikea, Spar, National Trust gift shops and Little Chef restaurants.

There are also trials involving Stagecoach buses in Liverpool and black cabs in London, while several UK music festivals are expected to go cashless next summer. This is all building up to the big one: the 2012 Olympics, which is being billed as "a contactless event," where visitors will be able to use their new plastic to pay for transport, tickets and refreshments.

Barclaycard this week claimed contactless payment was "reaching a tipping point". However, in spite of the company's high-profile waterslide and rollercoaster TV adverts, there are still many consumers who don't know what contactless is ... or who have one of the new cards but have been too nervous to use it because they are worried about security.

How does it work? Contactless cards use short-range wireless technology. The reader at the till picks up a signal from your card when it's very close.

How secure is it? This will be many people's big worry, and something that could hinder take-up. Card giant Visa insists it is "very secure".

The retailer has to enter the amount for you to approve, you then have to hold your card in front of the reader at precisely the right time – and for more than half a second. The reader display will confirm your transaction.

This means contactless payments cannot be made or duplicated without your knowledge, and there is no risk you'll be accidentally charged if you stand next to a reader, says Visa.

But what if someone steals my card? To combat the risk of a thief going on a contactless spending spree, cardholders will, when they hit a certain number of transactions or amount of spending, have to enter their pin the next time they pay, typically, each time they rack up £50 spending.

What's in it for me? Payments typically take 12.5 seconds, while processing a cash transaction takes an average of 34 seconds, and a pin transaction 27 seconds, according to Barclaycard. That should speed up queues.

Which banks and card companies are taking part? Barclays and Barclaycard are at the forefront, having issued 8m of the 10m cards in circulation. Halifax and Bank of Scotland have issued 650,000 debit cards so far, and targeted customers living in and around the M25, as that is where "the vast number" of merchant terminals are.

Meanwhile, Lloyds TSB plans to start issuing its cards in March, and will have 1.1m out there by the end of 2011. MBNA hopes to begin its rollout by the end of this year.

Royal Bank of Scotland/NatWest has been trialling them in London and Liverpool, and HSBC has been carrying out a similar exercise with 50,000 credit cards. By contrast, Nationwide, with 5 million current account customers, has no immediate plans to issue them. It says it is "something we are watching to see how it develops" and that, while a growing number of retailers accept the cards, they are "still very much the minority".

Which retailers are on board? A number of coffee shops and food chains, including Pret A Manger and Eat, were "early adopters". This year has seen a flurry of announcements. In June, Boots said 21 of its stores across London and Liverpool would soon be accepting contactless payments, and in July, the Co-op said its roll-out would begin with trials in 100 food stores and 50 pharmacies next year. Meanwhile, hi-tech new terminals are appearing in Spar shops and other locations.

But it's the big supermarkets that are needed to bring it into the mainstream. Tesco – with 2,482 stores – began testing in just one: a Metro in London's Dean Street. A spokesman says the initial response has been "very positive". Sainsbury's is understood to be looking at a trial within a year or so, while Waitrose is "trying to learn more about it".